The shearing machine used for transverse shearing of moving rolling stock is called flying shear. With the development of continuous steel plate rolling mills, section steel rolling mills and billet rolling mills and the improvement of flying shear productivity, the application of flying shears is becoming more and more extensive. There are many types of flying shears, which are widely used: disc flying shears, double drum flying shears, crank rotary and pendulum flying shears.
1. Disc flying shears
Such flying shears are generally used in small rolling mill workshops. It is installed in front of the cooling bed to roughly cut the rolling stock so that the rolling stock entering the cooling bed is not too long; or it is installed in front of the finishing rolling mill to cut the rolling piece to ensure the rolling process of the finishing rolling mill. went well. The flying shear is composed of two or more pairs of disc-shaped blades, and the axis of the disc is equal to the speed of the steel. When the shear is in the original position, the steel advances along the inlet duct to the left of the shear. When the steel acts on the flag switch or the light guide, the inlet guide and the steel are deflected to the right, and the steel enters the middle of the two discs for shearing. After the lower blade is lowered, the conduit returns the steel to its original left-hand position, after which the lower blade rises again. The disadvantage of this type of flying shear is that the incision is oblique, but it has little effect on the rough cut before the cutting head or the cooling bed. Because this shearing machine is reliable in operation, simple in structure, and has a shearing speed of more than 10m/s, it is widely used in small rolling mill workshops.
2. Double-drum flying shears
Double-drum flying shears are widely used in shearing steel and steel plates in motion. The working principle is as follows: On two rotating drums, two blades are radially fixed. The rolling stock moving along the roller table is cut by the two blades that meet when passing through the middle of the two rollers. The peripheral speed of the blade should be slightly greater than the moving speed of the rolling piece, otherwise the rolling piece will bend at the entrance when shearing. The disadvantage of this kind of flying shear is that the section is not smooth when shearing thick rolled pieces (too great influence on shearing thin rolled pieces); when cutting wide steel plates, the shearing force is large. Therefore, this flying shear is used to cut small sections and sheets of high-speed rolling stock.
Its shearing mechanism is composed of a four-bar linkage mechanism, and the shearing blade moves in an approximate plane in the shearing area and is perpendicular to the surface of the rolling piece. Therefore, the cut section of the rolled piece is relatively straight. The shearing mechanism of the flying shear is composed of a tool holder, an eccentric sleeve and a swing rod. The tool rest is in the shape of a lever, one end of which is fixed on the eccentric sleeve, and the other end is connected with a swing rod. The swing fulcrum of the swing rod is hinged to the column. When the eccentric sleeve (crank) rotates, the tool holder moves in translation, and the blade fixed on the tool holder can be perpendicular or approximately perpendicular to the workpiece. When shearing steel plates, an oblique blade can be used to reduce the shearing force. The disadvantage of this flying shear is that the structure is complicated, the dynamic load characteristics of the shearing mechanism are poor, and the movement speed of the blade cannot be too fast. Generally used for shearing thick steel plates or billets.
4. Pendulum flying shears
Such flying shears are sometimes used in cross-cutting trains in continuous steel mill workshops. The blade of this flying shear also moves in translation, and the quality of the cutting plate is better. The upper tool holder is fixed on the swing frame. The swing frame is supported on the eccentricity of the main shaft. There are two pairs of eccentrics on the main shaft, and the other pair of eccentrics is connected with the lower tool rest through the connecting rod, and the lower tool rest can slide in the chute of the swing frame. Since the two pairs of eccentric positions on the main shaft differ by 180°, when the main shaft rotates, the upper tool rest descends with the frame, and the lower tool rest rises to complete the shearing action. However, it can only cut stationary rolling stock. In order to be able to cut the moving rolling stock, it is necessary to enable the swing frame to swing back and forth. The lower part of the swing frame is hingedly connected with an eccentric rod, and the eccentric wheel is mounted on the rear axle. The rear axle is connected to the main shaft via pinions, racks and synchronizing discs. When the main shaft rotates, the frame can be oscillated back and forth with the main shaft as the center through the synchronizing disc, rack, pinion and eccentric connecting rod on the rear axle. At this time, the tool holder moves in translation to realize the shearing work of the pendulum flying shear. The role of the shearing machine in the rolling mill is not a key position, but it plays a crucial role in the accuracy and shape of the finished product. Different types of rolling mills need to choose the corresponding flying shears, so that the entire production line can achieve the goal. size and accuracy.
Post time: Sep-15-2022